How US cryptanalysts won WW II
Last night the Microsoft CTO office invited me to a private dinner party with 20 or so other security principals.
The speaker is from the NSA, the subtext is that they are looking for contributions for the new national cryptological museum. As sometimes happens at these events they throw out an interesting titbit to grab attention.
This time its a huge one.
The reason that the Allies chose Normandy for the D-Day landings and the reason they were able to fool the NAZIs into thinking that the attack would come at Calais. Critical to the deception was the ability to invade without performing reconnaissance.
The reason the allies could do this was that earlier the Japanese had become worried about the threat of an invasion and the NAZIs had taken a senior Japanese general on a tour of the Normandy defences. On completion of the tour he sends a 12 page report on what he has seen, including the placement of every gun emplacement, pill box, &ct.
The message is encrypted in the MAGIC cipher that the allies have already broken. The allies know everything they need to invade in Normandy and can thus engage in the critical deception designed to persuade the NAZIs that the invasion will come in Calais. All the reconnaissance is directed at Calais.
The deception succeeded and this success was critical in allowing the Allies to establish a beachhead in Normandy.
The role of the British cryptanalysts at Bletchley Park has been recognized for many years now. Until yesterday it had not been acknowledged that the US cryptanalysts had played such a decisive role in the European theatre.
